Shimano 105 5700 groupset, but with Tiagra 10spd derailleur?

daniel_b
daniel_b Posts: 12,038
edited August 2019 in Road buying advice
Hi all,

My brother has a 105 5700 10spd groupset.

As he lives in the mountains, the current 11-25 doesn't cut the mustard.

I was all set on a Tiagra 4700 medium cage rear derailleur, an 11-34 cassette, and a new chain.

But then I read this on CRC

"Due to a specific pull ratio, this derailleur is only compatible with Tiagra 4700 shifters"

I'm hoping the 700 model numbers being the same would mean they work, but does anyone know?
Felt F70 05 (Turbo)
Marin Palisades Trail 91 and 06
Scott CR1 SL 12
Cannondale Synapse Adventure 15 & 16 Di2
Scott Foil 18

Comments

  • super_davo
    super_davo Posts: 1,229
    No, different pull ratios on 4700 from other 10 speed Shimano.

    You can get way more than an 11-25 cassette on a 5700 mech though. There was a 12-30 Tiagra cassette when 4600 was out that should clear, assuming you can find one.
  • daniel_b
    daniel_b Posts: 12,038
    super_davo wrote:
    No, different pull ratios on 4700 from other 10 speed Shimano.

    You can get way more than an 11-25 cassette on a 5700 mech though. There was a 12-30 Tiagra cassette when 4600 was out that should clear, assuming you can find one.

    Thanks SD, found details that said the Tiagra 4700 is the only 10spd derailleur to have 11spd ratio. Wtf?

    So we decided to go with a medium cage 105 RD, and a Tiagra 11-34 rear cassette.
    He's going to gamble that the B screw will enable the 34 usage over and beyond the guaranteed 34.

    Just ordered it from CRC with free delivery to Italy.
    Felt F70 05 (Turbo)
    Marin Palisades Trail 91 and 06
    Scott CR1 SL 12
    Cannondale Synapse Adventure 15 & 16 Di2
    Scott Foil 18
  • bobones
    bobones Posts: 1,215
    One of these might be useful
    https://www.sjscycles.co.uk/gear-spares ... -extender/
  • daniel_b
    daniel_b Posts: 12,038
    bobones wrote:
    One of these might be useful
    https://www.sjscycles.co.uk/gear-spares ... -extender/

    That looks ace BB (and what a bargain), and I will bookmark that, as could come in useful if it's for a one off trip, or a hack, but as this is his best, and only roadbike, gonna stick with the new derailleur.
    Felt F70 05 (Turbo)
    Marin Palisades Trail 91 and 06
    Scott CR1 SL 12
    Cannondale Synapse Adventure 15 & 16 Di2
    Scott Foil 18
  • keef66
    keef66 Posts: 13,123
    It's beyond annoying that Shimano adopted the newer, hitherto 11 speed pull ratio for Tiagra 4700. It does mean that 4700 stuff works with 11 speed gear, but nobody's ever likely to want to do that

    You could always do what I did and fit a 9 speed MTB derailleur and a 10 speed 11-36 cassette. Spintastic!

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